Southern California head coach Clay Helton reacts to a penalty flag during the first half of an NCAA college football game against Arizona, Saturday, Oct. 15, 2016, in Tucson, Ariz. (AP Photo/Rick Scuteri)

Southern California tight end Daniel Imatorbhebhe (88) celebrates with Deontay Burnett (80) after scoring a touchdown during the first half of an NCAA college football game against Arizona, Saturday, Oct. 15, 2016, in Tucson, Ariz. (AP Photo/Rick Scuteri)

TUCSON, Ariz. (AP) — Sam Darnold is settling into the quarterback role at USC quite nicely, and he's got the Trojans in the thick of the race in the Pac-12 South.

The redshirt freshman, who didn't start until the fourth game of the season, threw five touchdown passes — three to JuJu Smith Schuster — in USC's 48-14 rout of Arizona on Saturday.

"There's a lot of stuff that I've learned these last few weeks that's really helped in this game," Darnold said, "and obviously games that we're looking ahead."

He completed 20 of 32 attempts for 235 yards and ran for 54 yards on six carries before sitting out the fourth quarter. He threw for 186 yards and four scores as USC built a 34-7 halftime lead.

"Not to blow his head up too much but he's playing really good football right now, way beyond his years, his maturity level," Trojans coach Clay Helton said.

Darnold was more upset about the plays he didn't make.

He said he is taking his job "week by week."

"If I progress, I progress" Darnold said. "That's part of growing, mentally and physically."

Smith-Schuster finished with nine catches for 132 yards.

The Trojans (4-3, 3-2 Pac-12) rolled for 575 yards and remained a half-game out of first place in the Pac-12 South. Arizona (2-5, 0-4) lost its fourth in a row.

USC won away from home for the first time since the interim label was removed from Helton's title. The Trojans had lost five straight away from home, dating to last season.

"This was a much-needed road victory," Helton said.

Wildcats true freshman Khalil Tate, just shy of his 18th birthday, completed 7 of 18 passes for 58 yards in his first collegiate start. Playing in place of injured Brandon Dawkins, Tate threw an interception and fumbled the ball away, leading to two USC touchdowns. He ran for 72 yards and a touchdown on 14 carries.

"He's a true freshman so we wanted to rattle him a little bit and get some hits on him," USC defensive back Chris Hawkins said.

Coach Rich Rodriguez said Tate is not the nervous type "...but there are times when a 17-year-old freshman looks like a 17-year-old freshman."

Rodriguez was asked what he'd say to fans that are unhappy with the Wildcats.

"We're 2-5. We've had some adversity," he said. "We can fix problems in recruiting and the other problems we can fix in the short term. People's opinions are people's opinions. We're not happy when we're not winning."

Arizona committed four turnovers, USC none.

"It was a huge emphasis this week in practice," Darnold said, "so it was on my mind the whole game. I just didn't want to turn the ball over."

The Trojans scored on their first and last possession and, early in the game, converted one third down after another. They were 4-for-4 on third down.

Adoree Jackson picked up a Tate fumble and returned it 26 yards to the Arizona 10 to set up the Trojans' third touchdown. Iman Marshall intercepted Tate's pass late in the first half and took it back 12 yards to the Wildcats 13-yard line, leading to another score that put USC up 27-7.

"I'm not sure what our quarterback situation is going forward," Rodriguez said, "but we have at least two weeks now to figure something out."

THE TAKEAWAY

USC: The Trojans are rolling. After opening conference play with losses to Stanford and Utah, USC has beaten Arizona State, Colorado and Arizona. California and Oregon are next before a Nov. 12 matchup at No. 5 Washington.

ARIZONA: The Wildcats have been hit by injuries, particularly at quarterback, and are in a tailspin that began with an overtime loss to then-No. 9 Washington.

UP NEXT

USC: After their first road win since coach Clay Helton had the interim tag removed, the Trojans don't play again until Oct. 27 against California.

ARIZONA: The Wildcats get their first bye since the 2014 season and they could use it to get Dawkins and others healthy. Arizona is home against Stanford on Oct. 29.